STEERING IS ACTING UP.

I was out doing some light offroadinq. My truck has a 187,000 mile on it but I have replace the rack and pinion and cv joints with boots a few years back. I have also replaced the strunt withint hte last 4 years. I used HD toyota parts. When I am turning my steering only get stiff every other time I turn. It get's a little worse after my truck it hot. I can push it to about 2000rpm and the steering work's ok. What can I check from the cheapest first.